Fastening Tool Movable Nose Assembly and Dry Fire Lockout
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Solution Overview
Problem
Pneumatic fastening tools often obstruct the operator's view due to the extended contact arm, making precise fastener placement difficult, and lack effective mechanisms to prevent dry firing when the nail supply is low.
Innovation Solution
A fastening tool with a movable nose assembly and a dry fire lockout mechanism that includes a contact trip assembly and a trigger assembly, where the movable nose is biased to a retracted position for improved visibility and a check pawl engages an opening in the upper contact arm to prevent initiation of the drive stroke when the nail supply falls below a predetermined number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact arm is extended beyond the nose tip to ensure actuation only after contact with the workpiece, then the safety and reliability of the fastening tool is improved, but the obstruction of the operator's view is worsened
Solution Approach 1:
The contact arm is divided into two separate components: the nose assembly that contacts the workpiece and the contact trip assembly that triggers actuation. This segmentation allows the nose to be retracted (improving visibility) while the contact trip mechanism remains functional (maintaining safety).
Solution Approach 2:
The movable nose acts as an intermediary between the contact arm and the workpiece. It transfers the contact force to the contact trip assembly without requiring the contact arm to extend beyond the nose tip, thus maintaining visibility while ensuring actuation safety.
2Ease of operation
If the contact trip assembly allows free movement for contact trip mode operation, then the ease of operation is improved, but the risk of dry firing when nail supply is low is worsened
Solution Approach 1:
The magazine assembly provides feedback about the fastener supply status to the contact trip assembly. When the fastener supply drops below a threshold, the magazine assembly restricts movement of the contact trip assembly, preventing dry firing while maintaining normal operation when supplies are adequate.
Solution Approach 2:
The system takes preliminary action to prevent dry firing by monitoring the fastener supply level in advance. When the supply is low, the magazine assembly proactively restricts contact trip assembly movement before a dry fire can occur, rather than reacting after the problem arises.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances precise fastener placement by reducing obstruction and prevents dry firing, ensuring accurate and efficient operation even when the nail supply is low.
Implementation Method 1
a movable nose assembly (22) carried by the housing and movable between a retracted position and an extended position
Implementation Method 2
a check pawl configured to engage an opening in the upper contact arm when the upper contact arm moves downward to prevent the tool from being operated in a contact trip mode
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fastening tool includes an actuation device configured to actuate a drive engine of the tool to initiate a drive stroke. The actuation device includes a contact trip assembly operatively connected to the movable portion of the nose assembly. The contact trip assembly a lower contact arm connected to the movable portion of the nose assembly biased in the retracted position and movable to the extended position with the moveable portion of the nose assembly, and an upper contact arm operatively connected to the lower contact arm. The actuation device includes a trigger assembly that includes a trigger, a trigger arm pivotally supported by the trigger and configured to interact with the upper contact arm, and a check pawl configured to engage an opening in the upper contact arm when the upper contact arm moves downward to prevent the tool from being operated in a contact trip mode.